Kinetics of Iron Sulfide Formation in Aqueous Solutions

Abstract

The formation of iron sulfides by spontaneous precipitation at 25 has been investigated in unstable supersaturated solutions by free-drift and constant supersaturation methods. In all cases an amorphous was formed which in the presence of atmospheric oxygen in the solutions was partially converted to pyrite. The spontaneous precipitation of amorphous was preceded by induction times inversely proportional to the solution supersaturation. The subsequent rates of precipitation were proportional to the solution supersaturation and showed a parabolic dependence on the relative supersaturation. At constant supersaturation and under a slight overpressure Mackinawite was identified as the initially forming phase with a plate-like and spherullitic morphology. The apparent order of the precipitation was found to be 1 which in connection with the results obtained from the free-drift experiments suggested a surface controlled